Polonium-210 is back in the spotlight. The radioisotope first gained notoriety back in 2006, after the death of Alexander Litvinenko, a one-time source for journalists who wanted to know about the inner workings of Russia.

Litvinenko, as the BBC tells it, went out to tea with two Russians at a hotel in London in early November of 2006. He drank some tea and by the end of the month he was dead, poisoned it turned out, by a tiny bit of Polonium-210, which decays quickly causing catastrophic damage if inside a human body.

-- With a half-life of 138 days it decays quickly, emitting alpha radiation. Outside the body, the IAEA says, a piece of paper or even a layer of dead skin could block alpha radiation from entering the body. But if inhaled or swallowed, it's deadly, rapidly destroying "major organs, DNA and the immune system."

-- And not much of it is needed to cause a ton of damage. As little as 3 millicuries, or an amount equal to a grain of salt, could kill a 154-pound human.

Deborah Blum, the author of The Poisoner's Handbook, wrote a piece about Polonium for Wired. She says Polonium wasn't Marie Curie's favorite discovery. She was much more interested in her "beautiful radium." In fact it was that radioactive element that came to find a central place in industrial and military settings. It was also Radium that was used in the early treatment of cancer.

The NRC points out that Polonium is mostly used for the dull purpose of removing static.

But the Litvinenko case and now Arafat have given Curie's stepchild some life, writes Blum, even if as "a poison for assassins."

For that, she says, it's almost perfect:

"A victim would never taste a lethal dose in food or drink. In the case of Litvinenko, investigators believed that he received his dose of polonium-210 in a cup of tea, dosed during a meeting with two Russian agents. (Just as an aside, alpha particles tend not to set off radiation detectors so it's relatively easy to smuggle from country to country.) Another assassin advantage is that illness comes on gradually, making it hard to pinpoint the event. Yet another advantage is that polonium poisoning is so rare that it's not part of a standard toxics screen. In Litvinenko's case, the poison wasn't identified until shortly after his death. In Arafat's case — if polonium-210 killed him and that has not been established — obviously it wasn't considered at the time."

But if you're an assassin there's one potentially fatal flaw. Polonium is extremely rare. The IAEA says it is produced in nuclear reactors and only 100 grams are produced each year.

What's more, so few produce it, says Blum, that tracing it to a state actor would be fairly easy.